We’ve been exploring CODA as an alternative to git hub
Both anecdotal evidence and academic research clearly indicates that users of knowledge management solutions are more likely to contribute to the corporate body of knowledge if the platform for capturing knowledge is easy to use and as painless for users to contribute. The counterpoint has also been demonstrated in that complexity in uploading and collaborating for enterprise knowledge acts as a barrier to sharing knowledge in a knowledge enterprises such as Lab49.
Github is a dog to use. It is not an intuitive solution; the support for semantically linking knowledge objects is weak; the administrative burden to add knowledge content is high. It is the poster child of what a enterprise knowledge solution should not be according to the academic research.